ilovebiking

In many of the threads that address light bikes, there is usually a couple of entries that basically say, "loosing a few pounds yourself is cheaper than paying extra for super light." So I was wondering if that is really true. Is body weight exactly comparable to body weight? For example, if I personally lost 2 pounds, will that have the same effect as buying a bike that is 2 pounds lighter than what I have? I just wan to understand this before I pay thousands for a super light climbing bike.

And what about wheel weight? Is that also equivalent to body weight? Bikers regularly pay a lot for a great lightweight wheel set. How does saving weight in the wheels compare to the rider just loosing some weight?

Thanks for any input.

Russ Roth

I would suspect on one level there's an equivalency but body weight fluctuates while a couple of pounds off the bike won't have any fluctuations; every upgrade in performance is an upgrade that will see you faster every ride until something like bearings get worn and need replacing or repacking. While the body weight can be canceled by a pint of Ben and Jerry's while snuggling with the wife. On the other hand if there is real weight to lose the benefits lie there; thinner people are more aero not to mention the other health benefits that will make you faster. But lets face it, I'd have an easier time dropping the weight from the bike and can still work at dropping it from the body.

Maelochs

Everyone knows that gravity's effects change depending on the chemical composition of the mass. Carbon fiber has vastly different gravitational properties than human fat, bone, or muscle, so weight lost in each substance will have vastly different performance effects.

mstateglfr 

I am 25-30# less now than around this time last year. I can for sure feel that while riding, but not really when climbing. I notice it more just in ease of sustaining power.
I am lighter, but my muscles are stronger/less fatigued and that is most noticable.

2# difference can't be felt. Not at all. Not in the least. Anyone saying they can feel 2# lighter overall when riding a bike is lying to you or to themselves. If an average enthusiast male cyclist is 170#, they are 190#(at least) with clothing and bike gear. Changing that to 188# is basically a 1% change in overall weight. Nope, not gonna feel it. And since many are over 170#, that weight difference is an even smaller % for them.


Wheel/tire weight can be easily felt when accelerating. It can't be felt when cruising along on flat road at 20mph.
Quality tires are probably the best place to find bang for your buck weight savings per dollar spent while also improving speed.

jpescatore

Wheel weight - I've always been told that reducing rotating weight (wheels, tires, cranks, pedals, chain ring, etc) would reduce needed power for a given speed more than just reducing bike and/or rider weight the same amount. The thought was that since you are constantly doing small accelerations while riding that rotating weight was more "power expensive."

Seemed to make sense but there is not a lot of science to support that, especially since rotating weight helps maintain wheel momentum when power is removed, too.

GCN did a video of some simple tests that showed the gains were minimal - .

Anecdotally, though: when I flatted a GP5000 32mm on my rear wheel and decided I try one of my heavier Schwalbe Marathons which never flat, I could immediately feel the difference in getting started from dead stop. Could be psychological, 30% of people benefit from placebos, after all. But, I put back on the GP5000 after a few weeks!

DaveSSS 

A simple answer is that body weight is just as important as bike weight. Reduced weight is most important when climbing. Heavy guys can do well on the flats, but as soon as the road turns upward, they won't keep up with the light weights. That's why paying $2000 more for a frame that's less than a pound lighter is silly for most riders. I'm light at 134 pounds, but if I was a pro rider I'd probably be considered fat unless I was under 130.

Some will say that they know a heavy rider who climbs well, but if the extra weight is fat, then that person would climb faster without the excess weight.

mstateglfr 

I see comments like this a lot and don't understand.
A lot of pro rider info i see shows most are about 5'8-6'0 tall and weigh 130-160#.
Admittedly i don't look often and don't follow UCI beyond cursory wiki pages really, but still- are the numbers I see that I see somehow wrong?

Besides a jockey, I cant imagine where a male athlete must be under 130# to not be fat.

WhyFi

A few pounds can dramatically change the feel of a bike, though you probably wouldn't be able to see a difference on a stopwatch.

bruce19

Search GCN

Iride01 

If you loose every pound you can from your body and your bike is heavy, then you still have more to loose.

People on a diet marvel about loosing five pounds of water weight in their first week of dieting. Why not also get a bike that's five pounds lighter and marvel at that too?

Weight is weight. Lose it from what ever you can if your numbers mean that much.

Seattle Forrest

It's really very context dependant. Aero road bikes are generally heavier than regular ones, and faster except uphill. Lighter bikes are easier to move around under you. A lighter bike is easier to pick up and carry. Depending on your body composition a heavy bike isn't bad for your health.

Maelochs

I did an informal experiment with my Fuji Sportif---rode it a bunch with the stock boat-anchor wheels and granite tires, then rode it a bunch more with lightweight Vueltas and Conti GP GTs, then rode it a whole bunch more with lightweight CF wheels and the same tires, and also Hutchinson Fusion 5s.

Very noticeable improvement in acceleration with each improvement. Very noticeable---even to me, and I am not the most sensitive guy in the crowd.

A whole lot of people have posted similar threads about how changing wheels made a huge and very noticeable improvements in bike feel.

It's not that I don't trust science---but I sure don't trust a lot of scientists. hen some guy tells me, "I have a website--therefore I have infinite wisdom," I have doubts. When he follows up by telling me "Don't believe your eyes---believe what i tell you" ....

Branko D

The difference when you change tires and tubes is hugely significant. The quality of the bearings between cheapest of the cheap (OEM wheelset) and decent can have a slight difference in performance. Effective suspension is different between different internal width rims on the same tire and inflation pressure.

​​​​The "I changed my wheelset and the tires and the bike was totally different" being pegged on difference in wheel weight is strange. Mathematically, weight of wheelset makes about 110-120% difference in acceleration than static mass difference does and that's it.

There is no reason to distrust the math:
​​​if I take my body weight, my bike plus water weight, length and slope of climb and my power in cycling calculator, I get pretty much the same time I actually took on the climb (on shallow climbs the wind / aero messes it up, but climbing serious stuff, the math is very predictive). This works as well as you'd expect with a 1450g, 1750g and a 2050g wheelset.

Weight is weight and it makes you accelerate and climb slower, whether it's on you or on the bike.
​​​​

WhyFi

No, it's not strange at all - it does change the feel of the bike significantly, not because it's going faster, but because it's easier to move around underneath you. Particularly when accelerating, people tend to get out of the saddle and rock the bike side-to-side - lighter wheels make the bike less resistant to this movement (this applies to cornering, too).

If you want to demonstrate to yourself, take a wheel off your bike, holding both ends of the skewer/TA, give the wheel a good spin and make note of how difficult it is to tilt one way and then the other. Next, take off the tire and tube and do it again - dollars to donuts, it'll be noticeably different minus that few hundred grams. If you want to stick to maths, rather than practical demonstrations, I guess that would fall under flywheel weights and moment of inertia, but I'm no physicist.

As I said previously, I don't believe that these kinds of differences will demonstrably improve speed, 'specially solo over a given course, but will they make the bike feel totally different? Absolutely.

CoachPC

In my opinion weight is weight; riding a bicycle is combination of Body + Bike Weight.

If I lost 3lbs of body weight or decided to ride by removing 3lbs of component weight from my bike the total weight reduced is still the same.

When I lost 10lbs one summer I was as fast as I had ever been on the bike - I could never find a way to remove 10lbs of component/frame weight from my bike (it only weighs 14lbs as it is).

DaveSSS 

I'm only 5'-6" and have more upper body muscle than any climber type pro cyclist. I can't imagine that some don't get into the 120s. My lowest has been 131, but have a little fat left to pinch in a few areas.

wphamilton

Conventional wisdom is that bike weight matters more for light cyclists than heavy ones. So I decided to let myself gain weight, so that my heavy bike won't matter as much.

TonyMTL

Very interesting stuff in the replies here...

I’m 225lbs, my bike is 20lbs. One of my friends told me that having a bike between 15-18lbs would be better for me and help me be faster and better on climbs.

Will 2-3lbs really help me that much? I mean to make my bike lighter I’d have to spend a good $700 on carbon fork, light seatpost, handlebar, stem, and another $500 on an ultralight crank (yeah those light cranks who are said to sometimes delaminate or come apart after a few years). I’m
wondering if it’s all really worth $1k? Will it make a significant improvement?? Or should I just lose 20lbs of fat and become as skinny as I can be?

mattscq

Losing body weight does reduce your frontal area; therefore more aero.
Losing bike weight tends to mean less aero optimized frames.
Either way, neither makes a difference with my FTP of an Easybake oven.

WhyFi

Losing 20lbs will help considerably on the climbs - been there, done that.

kingston 

I'm into randonneuring, so average speed is an important metric for me, which I realize is not the case for everyone. For the kind of recreational distance cycling I do, body weight is much more important than bike weight. I let my weight get up to 215 several years ago, from my normal 165. My lightest brevet bike is around 20 pounds, my heaviest is almost 50. I can say with absolute certainty that I am faster as a 165 pound human on a 50 pound bike than a 195 pound human on a 20 pound bike. At the same weight, I'm only marginally faster on the lighter bike if the course has a lot of big hills. Flat or rolling course, average speed is pretty much the same on a 20 or 50 pound bike. I rode a flatish 200k a few weeks ago on my 50 pound bike and stayed with the same group of guys I normally ride with on my lighter bike. If average speed is the metric, bike weight is just not as important as fitness.

ridelikeaturtle

Look up Weber's Law and how it relates to perception. What is equivalent isn't always perceived as equivalent; e.g., adding (or removing) 1kg to/from 100kgs is just 1%, and significantly less noticeable/perceivable than adding/removing 1kg to 20kg (5%).

rubiksoval

Of course. Why wouldn't it?

Actually, for substantial weight loss from the body, you're likely improving such things as comfort, and potentially even aerodynamics as well (in regards to being able to tuck down and not kneeing yourself in the gut, and being thinner and having less of yourself poking out to the sides and catching wind...).

Litespud

weight is weight, at the end of the day. However that 2lb off the bike will likely be noticeable because it occurs instantaneously - losing the equivalent 2 lb off your arse takes days or weeks - you’d never register that small gradual change

WhyFi

You can lose two pounds of water weight in an hour or two of riding.